This invention relates to a honeycomb structure used as a substrate of catalysts for purifying exhaust gases from internal combustion engines, as a filter for removing fine particles in exhaust gases, and as a substrate of various catalysts for deodorizing and/or purifying burnt gases when fuels such as various gases or petroleum are burnt. More particularly, the invention relates to a method of producing such a honeycomb structure.
FIG. 1 illustrates a catalyst converter which has been generally practically used for purifying exhaust gases from an automobile loaded with the converter. In order to prevent damage to the converter during violent vibrations in use, it comprises cushion members 12-1 and 12-2 and sealing members 12-3 about a honeycomb structure having through-apertures 11-1 through which exhaust gases pass and plate members 13 on upstream and downstream sides of the structure. The cushion members and the sealing members apply forces upon the honeycomb structure in traverse or lateral directions (referred to as "radial directions" hereinafter) of the directions of the through-apertures 11-1 and the plate members 13 apply forces directly or through the cushion members 12-1 onto the honeycomb structure in the directions of the through-apertures 11-1. The honeycomb structure is fixed and held thereat in this manner.
With such a construction of the catalyst converter, however, the cushion members 12-1 or the plate members 13 close some apertures 11-2 of the through-apertures 11-1 so that exhaust gases do not pass through the apertures 11-2, with the result that the catalyst carried by the portions of the apertures 11-2 will be inoperative.
In order to avoid this disadvantage, it has been practically proposed to hold a honeycomb structure in radial directions only by seal members arranged radially outward of the honeycomb structure for the purpose of saving catalytic noble metals.
With the limitedly practically used honeycomb structure being only radially supported, however, high pressure is required to radially support the structure in order to fix it against movement or damage caused by violent vibrations generated in use. It is possible to support it radially in case that thicknesses of partition walls of the ceramic honeycomb structure are comparatively thick, for example, 0.3 mm to provide a high strength against external pressures. However, such a supporting of the honeycomb structure is not applicable to a honeycomb structure whose partition walls are relatively thin such as 0.15 mm to 0.20 mm and susceptible to external pressures. Therefore, with the prior art a honeycomb structure high in reliability could not be obtained.